Cyclists on self driven bicycles often take bottles of liquid with them to quench their thirst. In order to minimize weight and to carry as much liquid as possible without too much bulk, the bottles are usually made of thin plastic having little if any thermal insulation value. Whereas, the temperature of the liquid does not change too much during short trips, it becomes too hot or cold on trips of 1/2 hour or longer.
It has been customary for a bottle to be nestled in a flexible cage that is securely attached to a bar of the bicycle. In U.S. Pat. No. 4,883,205 entitled "Insulated Bottle Rack Apparatus for Bicycles" that was issued to William R. Saelens et al on Nov. 28, 1989, just the body portion of the bottle is insulated by a hollow cylindrical sleeve of insulating material having a closed end. The sleeve fits over the cage and between the cage and the bar to which the cage is attached by bolts. Openings are formed in the sleeve through which the bolts are passed. No provision is made for insulating the top of a bottle held within the cage. Furthermore, there is an opening in the closed end that permits air to flow in between the insulation and the bottle so as to reduce the insulating effect. In situations where insulation is not required, one must inconveniently remove the bolts before the insulating sleeve can be removed.